Dictionary.com
definitions

vigintillion

[vahy-jin-til-yuh n]
noun, plural vi·gin·til·lions, (as after a numeral) vi·gin·til·lion.
  1. a cardinal number represented in the U.S. by 1 followed by 63 zeros, and in Great Britain by 1 followed by 120 zeros.
adjective
  1. amounting to one vigintillion in number.

Origin of vigintillion

1900–05; < Latin vīgint(ī) twenty + -illion, as in million
Related formsvi·gin·til·lionth, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018